What is the noise figure of a receiver?
The correct answer is D: The ratio in dB of the noise generated by the receiver to the theoretical minimum noise. What is the noise figure of a receiver is the ratio in dB of the noise generated by the receiver to the theoretical minimum noise. Noise figure compares receiver noise to ideal (thermal) noise. For amateur radio operators, this is important for receiver performance. Understanding this helps when evaluating receivers.
Exam Tip
Noise figure = ratio in dB of receiver noise to theoretical minimum noise. Think 'N'oise 'F'igure = 'N'oise 'F'rom receiver vs 'I'deal. Noise figure compares receiver noise to ideal (thermal) noise. Not atmospheric/phase noise, not bandwidth ratio, not atmospheric noise - just receiver noise vs theoretical minimum.
Memory Aid
"Noise figure = ratio in dB of receiver noise to theoretical minimum noise. Think 'N'oise 'F'igure = 'R'eceiver vs 'I'deal. Noise figure compares receiver noise to ideal (thermal) noise. Important for receiver performance."
Real-World Application
The noise figure of a receiver: It's the ratio in dB of the noise generated by the receiver to the theoretical minimum noise (thermal noise). A perfect receiver would have 0 dB noise figure. Real receivers have higher noise figures. This is what noise figure is - receiver noise vs theoretical minimum.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Ratio of atmospheric noise to phase noise isn't noise figure - noise figure is receiver noise vs theoretical minimum. Atmospheric/phase noise isn't noise figure.
Option B: Incorrect. Ratio of noise bandwidth to theoretical bandwidth isn't noise figure - noise figure is receiver noise vs theoretical minimum. Bandwidth ratio isn't noise figure.
Option C: Incorrect. Ratio of receiver noise to atmospheric noise isn't noise figure - noise figure is receiver noise vs theoretical minimum. Atmospheric noise isn't the reference.
题目解析
The correct answer is D: The ratio in dB of the noise generated by the receiver to the theoretical minimum noise. What is the noise figure of a receiver is the ratio in dB of the noise generated by the receiver to the theoretical minimum noise. Noise figure compares receiver noise to ideal (thermal) noise. For amateur radio operators, this is important for receiver performance. Understanding this helps when evaluating receivers.
考试技巧
Noise figure = ratio in dB of receiver noise to theoretical minimum noise. Think 'N'oise 'F'igure = 'N'oise 'F'rom receiver vs 'I'deal. Noise figure compares receiver noise to ideal (thermal) noise. Not atmospheric/phase noise, not bandwidth ratio, not atmospheric noise - just receiver noise vs theoretical minimum.
记忆口诀
Noise figure = ratio in dB of receiver noise to theoretical minimum noise. Think 'N'oise 'F'igure = 'R'eceiver vs 'I'deal. Noise figure compares receiver noise to ideal (thermal) noise. Important for receiver performance.
实际应用示例
The noise figure of a receiver: It's the ratio in dB of the noise generated by the receiver to the theoretical minimum noise (thermal noise). A perfect receiver would have 0 dB noise figure. Real receivers have higher noise figures. This is what noise figure is - receiver noise vs theoretical minimum.
错误选项分析
Option A: Incorrect. Ratio of atmospheric noise to phase noise isn't noise figure - noise figure is receiver noise vs theoretical minimum. Atmospheric/phase noise isn't noise figure. Option B: Incorrect. Ratio of noise bandwidth to theoretical bandwidth isn't noise figure - noise figure is receiver noise vs theoretical minimum. Bandwidth ratio isn't noise figure. Option C: Incorrect. Ratio of receiver noise to atmospheric noise isn't noise figure - noise figure is receiver noise vs theoretical minimum. Atmospheric noise isn't the reference.
知识点
Noise figure, Receiver, Ratio in dB, Noise generated by receiver, Theoretical minimum noise
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.